DESCRIPTION: The primary purpose of this research is to study the gustatory response properties and central terminal fields of single taste neurons of the GSP and CT nerves in the rat, nerves that innervate populations of gustatory receptors on the mammalian palate and anterior tongue, respectively. These fundamental data are lacking because of difficulty in gaining access to the ce bodies, located in the geniculate ganglion, in vivo. The principal investigat has developed a surgical preparation that provides reliable experimental acces to neurons in the geniculate ganglion. This permits neurophysiological recordings from individual GSP and CT cells to describe in detail the response properties of these intact gustatory neurons. The cells will then be injected with neuronal tracers to define the central terminal fields of the functionall characterized neurons. Together, these data will provide the opportunity to identify structure-function relationships in these primary sensory neurons. A minor component of the application is a single experiment in which integrated taste responses from the GSP nerve will be made in 12 adult rats that received bilateral transection of the CT nerve at 10 days postnatal. This study will determine whether changes in GSP activity are associated with a previously demonstrated alteration in taste preference behavior and will contribute to a line of research that investigates the long-term neurobiological consequences neonatal CT transection.